This invention relates to a method of and an apparatus for feeding a filler member or cord with respect to an interlocking element for a slide fastener during the formation of such element.
As is well known in the art of slide fasteners, filler cords usually made of a textile material are employed to assist in retaining the proper position and function of a fastener element such as for example in the form of a continuous helical coil when the latter is secured to a longitudinal edge of the fastener tape. It is known to insert the filler cord into and through the space extending longitudinally of the convolutions of the coil element simultaneously as they are progressively formed and transported.
According to one such known method and apparatus, the filler cord wound on a bobbin is first withdrawn by a swinging or rotating member and further pulled out, while it is somewhat slackened, by means of a rotary screw associated with a fastener element forming and transporting mechanism. When it is fed while being held slack, the cord tends to become irregular in its reversely directed or back tension, hence vary over a given length, become twisted, improperly positioned, deformed or otherwise result in defective fastener products.